Hexa-substituted benzenes as resin stabilizers



United States Patent 3,102,870 HEXA-SUBSTITW'ED BENZENES AS RESINSTABIMZERS Kenneth R. Mills, Boris Franzus, and Peter J. Canterino,Bartlesville, @lrla, assignors to Phillips Petroleum Company, acorporation of Delaware No Drawing. Filed (let. 2, 1959, Ser. No.843,919

' i 20 Qlaims. (El. 260-4537) This invention relates to hexa-substitutedbenzenes as resin stabilizers.

Many of the polymers used in the plastics industry exhibit insuflicientinherent stability when exposed to light. Ultraviolet light isparticularly troublesome. 'l he resins become brittle, show loss intensile strength, and their surfaces become chalky, in extreme casesshowingfchecking or cracking.

The following are objects of our invention.

An object of our invention is to provide new compositions comprising anultraviolet sensitive polymer and a small quantity of a hydrocarbonhem-substituted benzene. A further object of our invention is to improvethe resistance of olefin polymers, such as polyethylene, to ultravioletlight.

Other objects and advantages of this invention will be apparent to oneskilled in the art upon reading the accompanying disclosure.

Broadly, our invention resides in the production of new compositionscomprising an ultraviolet sensitive polymer and a small quantity of ahydrocarbon hexa-substituted benzene.

We have now found that by incorporation of a small quantity, say from0.1 to 10 parts by weight of a hexasubstituted benzene in 100 parts of apolyoleiin resin, deterioration from the effects of exposure toultraviolet light is inhibited over extended periods of time. Theamountsgiven are by way of example. Generally the improvement is proportionalto the amount of additive used.

The hexa-substituted benzenes used in the present invention arecompounds having the general formula tion of hexa-substituted benzenesin which all substituents are identical comprises trimerization ofsymmetrical idisubstituted acetylenes using catalyst systems comprisinga metal hydride or organometal compound of a metal of groups I, H, orill of the periodic system, including compounds wherein one or more butnot all the organic groups are replaced by halogen, together with a saltor alcoholate of a metal of group IV, V, VI, or Vlll, these componentsbeing present in a mole ratio between :1 and 50:1.

This is the method disclosed by Franzus et al. in application Serial No.763,831, filed September 29, 1958, now abandoned, wherein the catalystsystem is more specifically disclosed :as comprising (A) metal hydridesor organometal compounds of metals of groups I, II, and III of theperiodic system, including compounds wherein one or more but not all theorganic groups are replaced by halogen, together with (B) a chloride,bromide, iodide, oxychloride, oxybrornide, oxyiodide, or alc'oholate oftriice valent iron, trivalent cobalt, trivalent nickel, tetranalenttitanium, tetravalent zirconium, tetravalent hafnium, tetravalentthorium, tetnavalent germanium, tetraualent tin, tetravalent lead,tetravalent platinum, tetravalent osmium, tetravalent iridium,pentavalent vanadium, pentavalent niobium, pentavalent molybdenum,pentava-lent tungsten, pentavalent uranium, and hexavalent chromium. Itis preferred that these components be present in a mole ratio of (A) to(B) of at least 05:1 and more preferably 'at least 1:1.

Suitable hydrocarbon hem-substituted benzenes includehexa-phenylbenzene, hexa-l-naphthylbenzene, hexa-2- naphthylbenzeue,hexa-methylbenzene, hexa-ethylbenzene, hexa-dodecylbenzene,hexa-cyclohexylbenzene, hexa-cyclopentylbenzene, hexa-benzylbenzene,hexa-p-tolylbenzene, hexa-(3-eth'ylphenyl)benzene, l,4-diethyl-2,3,5,6tetramethylbenzene, 1,2 diphenyl-3,4,5,6-tetraethylben zene,2,3,4,5,6-pentaphenyltoluene, 1,4- dinaphthyl-2,3,5,6tetraphenylbenzene, 1,4-dimethy1-2,3-diphenyl-5,6-diethylbenzene,1,2,3-triphenyl-4,5,6-trimethylbenzene,l,2-:'(llbenzyl-3,4-dimethyl-5,o-diphenylbenzene,hexa-(Z-phenylethyDbenzene, hexa-tert-butylbenzene andhexa-isopropylbenzene.

The preferred hexa-substi-tuted benzenes are those in which allsubstituents are identical, and still more prefer table are thehexa-phenylbenzenes in which, referring to the general formula above, Ris a phenylor substituted phenyl or naphthyl group. They can contain. asmany as 60 carbon atoms in the sum of the substituent groups Theadditives of the present invention have a high degree of compatibilitywith the polyolefin in which they are incorporated. A convenient method-for their incorporation is by addition on a roll mill operated at atemperature in the range between 275 and 400 F.

The resins in which the stabilizers of our invention are used include,broadly, those which are sensitive to ultnaviolet light. These include,for example, polyethylene, polypropylene, ethylene-propylene copolymers,poly(vinylchloride), poly(viny1 acetate), vinyl chloridevinyl acetatecopolymers, and poly(vinylidene chloride). The stabilizer can be usedalone or together with other additives such as fillers, antioxidants,pigments, etc. Mixtures of stabilizers can be used.

The following example illustrates a specific embodie ment of ourinvention. The polyethylene was prepared according to this method ofHogan and Banks 2,825,721

and had :a density of 0960:0001, a melt index of A series of runs wasmade in which hexa-phenyl-benzone was incorponated in polyethylene on a.roll mill at 300 F., using a milling period of 10 minutes, in amountsvarying 'from 0.5 to 6.0 percent and tested in a Weatherometer (AtlasWeatherOmeter), by which an accelerated ultraviolet treatment wasprovided. In these runs, the polymer containing the additive wascompression molded to form a slab from which tensile bars were cut. Anumber of these bars were exposed and removed individually over a periodof time for tensile determination. The values obtained were distributedon a graph and the hours exposure to a drop in tensile of 50 percentdetermined as the evaluation for the sample. Data from these tests areshown below:

Table I Amount heXa-phenyl- Time to 50% tensile benzene percent (hours)None 0.5 300 1.0 375 of heXa-phenylbenzene.

' In all the above tests, the additive appeared to be com- I pletelycompatible, as indicated by absence of bleeding.

As many possible embodiments can be made of this invention without'depanting tflrom the scope thereof, it is to be understood that allmatter herein set forth is to be interpreted as illustnative and not asunduly limiting the invention. I i

- We claim:

1. An ultraviolet sensitive polymer selected from the group consistingof homopolymers of ethylene, propylene,

vinyl chloride, Vinyl acetate, vinylidene chloride, and g copolymers ofthese monomers and a stabilizing amount of a heXaaryl-substitutedbenzene.

2. An ultraviolet sensitive polymer selected from the" group consistingof homopolymers of ethylene, propylene, f vinyl chloride, vinyl acetate,vinylidene chloride, and copolymers of these monomers containing, per100 parts by weight, 0.1 to 10 parts of a heXa-aryl-substituted benzene.

3(Polyethylene containing a stabilizing amount of a hexa-arylsubstitutedbenzene.

Polyethylene containing, per 100' parts by weight,

"0.1' to 10 parts of a hexa-aryl-substituted benzene.

5. Polyethylene containing, per 100 parts by Weight, 0.1 to 10 pants ofhexa-phenylbenzene.

6. Polyethylene containing, per 100 parts by Weight, 0.5 to 6 parts ofheXa-phenylbenzene.

7. An ultraviolet sensitive polymer selected from the group consistingof homopolymers of ethylene, propylene, vinyl chloride, vinyl acetate,vinylidene chloride, and copolymers of these monomers and a stabilizingamount 8. Polypropylene containing 9]. An ethylene-propylene copolymercontaining a stabilizing amount of a hexa-aryl-substituted benzene.

10. Poly ('vinyl chloride) containing a stabilizing amount of aheXa-aryl-substituted benzene.

a stabilizing amount of a heXa-aryl-substimted benzene.

2 I 11. Poly(vinyl acetate) containing a stabilizingamount of ahexa-aryl-substituted benzene.

12. A'vinyl chloride-vinyl acetate copolymer containing a stabilizingamount of a heXa-aryl-snbstituted benzene.

13. Poly(viny1idene chloride) containing a stabilizing amount of ahexa-aryl-snbstituted benzene.

14. Polypropylene containing a stabilizing amount of hexa-phenylbenzene.

15. An ethylene-propylene copolymer containing a stabilizing amount a ofheXa-pheny-lbenzene.

1 6'. Poly(viny1 chloride) containing a stabilizing amount ofheXa-phenylbenzene,

17. Poly(vinyl acetate) containing a stabilizing amount ofheXa-phenylbenzene.

18. A vinyl chloride-vinyl acetate copolymer containing a stabilizingamount of hexa-phenylbenzene.

19. Poly(vinylidene chloride) containing a stabilizing amount ofhexa-phenylbenzene.

20. Polyethylene containing a stabilizing amountof heXa-phenylbenzene.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES,

Nakamoto: 74 Journal Amer. Chem. Soc. 390 (1952),

page 391.

1. AN ULTRAVIOLET SENSITIVE POLYMER SELECTED FROM THE GROUP CONSISTINGOF HOMOPOLYMERS OF ETHYLENE, PROPYLENE, VINYL CHLORIDE, VINYL ACETATE,VINYLIDENE CHLORIDE, AND COPOLYMERS OF THESE MONOMERS AND A STABILIZINGAMOUNT OF A HEXAARYL-SUNSTITUTED BENZENE.